I’m a bit astonished by how different the experiences are between people with the same or similar iPhones. For some people it’s one of the best versions, for others is a battery nightmare.
I think that shows the complexity of things.
There can be many reasons why we see good or bad batterytime and its not only related to OS updates, or more so, its more than the OS that can cause battery drain.
Apps can cause battery drain and sometimes people do forget to update their apps when they update the OS.
One OS version can with one particular app version cause battery drain.
Other reasons can be:
* We all have different configured phones (settings, background activities, memory usage and models)
* Some models even if its the same model have different HW
* We live in different locations with different networks, a US phone and a EU phone can have different hardware when it comes to the comms part
* We use them differently
* We don't know the status of the phone, how old is the battery, is it damanged?
** When we compare we generally do it with how the phone was when we got it.
* Mayor updates have new features that can be more CPU intensive
* Some security patches can have an impact on performance
+ many more reasons...
But today there aren't a reason not to update, some of the updates fix major bugs and security issues.
And its not only about protecting the user of the phone, its also about protecting the users contacts that's also have data on the device.
People seem to forget that they are carrying data about friends, work etc that also need to be protected